JP3449304B2 - Recording track running characteristic evaluation method, recording track running characteristic evaluation device, reference tape running characteristic evaluation device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape running characteristic evaluation method and device for a recording track, which can easily evaluate a tape running characteristic of a recording track in a special reproduction in which a reproduction is performed across a recording track.

[0002]

2. Description of the Related Art An important point in magnetic recording / reproduction is that a recording signal is reproduced without any problem even when a tape recorded by one device is reproduced by another device. That is, compatibility is important. By the way, the check of the form of the recording track recorded on the magnetic tape in a certain device is usually performed by measuring the track pattern. When the track pattern is developed with a special colloidal liquid containing magnetic fine particles, a recorded image appears on the magnetic tape as shown in FIG. The measurement is usually performed using a measuring microscope.

As a concrete measuring method, y0 in FIG.
Basically, y1, y2, ... Yn are obtained and, for example, the pattern deviation from the standard pattern of VHS (registered trademark) is calculated. The actual measurement is Y on the control signal, Y
1, Y2 ... Yn can be used as an alternative. Also in this case, the pattern deviation (D0, D1, D2 ... D from the standard pattern of VHS (registered trademark))
n) is obtained, and this represents the linearity of the video track itself as shown in FIG. Then, in reality, the running state of the tape is estimated by evaluating the linearity of the video track. This calculation requires correction of the tape speed obtained from the pitch of the control signal.

[0004]

By the way, in a normal analog VTR, even if there is a change in tape running due to wow / flutter, jitter, or vertical movement in the tape width direction during special playback, the noise bar will rise or fall to some extent. This is not a big problem, but it is a digital VTR, especially D-VHS (registered trademark)
In this case, the special reproduction data is placed only at a predetermined position on the helical track, and an image cannot be composed unless all the special reproduction data are prepared, so it is necessary to strictly manage tape fluctuations during special reproduction. is there. If the normal tape running state (REC / PLAY) can be evaluated with the conventional technology without problems, it is impossible to record in the special playback (search / slow / still) state with a normal device, and modification is required. Therefore, at present, it can be evaluated only with a prototype. Also,
Even if the tape is modified so that it can be recorded in the special playback state, if the tape running fluctuation is large, the track running condition cannot be fully grasped unless the track linearity measurement is 10 to 20 data. take time. Therefore, the advent of an apparatus for evaluating running characteristics of recording tracks during special reproduction in a digital VTR has been awaited.

[0005]

The present invention SUMMARY OF THE INVENTION has been made in view of these problems, as a first invention, by special reproduction I traverse an inclined track recorded at the standard speed on the recording medium , The special playback of the inclined track
In the method for evaluating the running characteristics of a recording track for evaluating the running state, the playback start position for performing the special playback and the playback start position
A measuring step A of measuring the time base fluctuation of the reproduced output of each track to be played in succession, the measuring step A
Calculates the position of the recording track with respect to the maximum value and the minimum value or <br/> et playhead time base fluctuations as measured by,
The running characteristic evaluation method of the recording track to be and a evaluation step B for evaluating the running state of the recording track at the time of special reproduction, as a second invention, transected oblique tracks recorded at normal speed on a recording medium By special playback,
In the running characteristic evaluation apparatus of the recording track to assess the tape running state at the time of special reproduction of the inclined track, the Japanese
The playback start position for special playback and the subsequent playback
Measuring means A for measuring the time base fluctuation of the reproduced output of each track that the time axis measured by the measuring means A
A third aspect of the present invention is a tape running characteristic evaluation device, which is provided with an evaluation means B for calculating the position of a recording track with respect to a reproducing head from the maximum value and the minimum value of fluctuation and evaluating the tape running state during special reproduction. As a standard speed on the recording medium.
By linearity of the recording has been inclined tracks are special reproduction I traverse the oblique tracks of the reference tape is known, the travel of the recording track of the reference tape for evaluating the tape running state at the time of special reproduction of the inclined track In the characteristic evaluation device, the reproduction start position for performing the special reproduction and the
Measuring means A for measuring the time-axis fluctuation with the reproduction output of each track which is continuously reproduced, and the maximum and minimum values of the time-axis fluctuation measured by this measuring means A , from the recording track to the reproducing head. A reference tape running characteristic evaluation device is provided, which is provided with an evaluation means B for calculating the position and evaluating the running state of the reference tape during special reproduction.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings with reference to FIGS. Figure 3
[FIG. 3] is a track pattern for explaining the tape running characteristic evaluation method and device of the present invention. D-VHS (registered trademark)
According to the standard, data is arranged in a certain range in which a head locus in special reproduction (hereinafter referred to as trick play) is centered on an intersection point across a recording track. In order to evaluate the tape fluctuation from the reproduction data ID and the time-axis fluctuation amount of the reproduction output, it is necessary to obtain the standard trick play data center (burst center) position. FIG. 3 shows a method of calculating intersection coordinates in trick play in the reverse direction (hereinafter referred to as reverse). FIG. 4 is an explanatory diagram showing a converted state of the recording track displacement, FIG. 5 is an explanatory diagram showing an evaluation result by tape pattern measurement, FIG. 6 is an explanatory diagram showing an evaluation result by a reproduction data ID, and FIG. FIG. 8 is an explanatory view showing an embodiment of the measuring means of the recording track running characteristic evaluation method and apparatus according to the present invention, and FIG. 8 is an example of the evaluating means of the recording track running characteristic evaluation method and apparatus according to the present invention. FIG. 9 is an explanatory diagram showing the method of calculating the maximum value and the minimum value, and FIG. 9 is an explanatory diagram showing the evaluation result of the output time axis fluctuation measurement.

<Background of the Invention> It is assumed that the reverse head locus is tracked at the drum winding 0 [°] position of the recording track, and this is the origin of coordinates, and the nth intersection coordinates are x and y. Where θ [°] is the recording track angle, θt [°] is the head track angle of trick play, and W
[Mm] is an effective data area (video width). ν [m
m] is the distance that the tape moves while the drum rotates 1/2 rotation, and is half the tape speed Vt [mm / s] divided by the drum rotation speed N [s ^-1 ].

When x and y are obtained from FIG. 3, (1) and (2)
It becomes an expression. However, in Forward, θ <θt, and θ and θt are reversed in the denominator of x and y. y / x = tan θt (1) y / (x−n · ν) = tan θ (2) When x and y are calculated from the equations (1) and (2), (3),
It becomes the formula (4). x = n.v.tan .theta. / tan .theta.-tan .theta.t (3) y = n.v.tan .theta..tan .theta.t / tan .theta.-tan .theta.t (4) Since the number of sync blocks (hereinafter referred to as SB) per track is 356, 356 / W [SB /
mm] to obtain the SB number of the burst center. Also, y is divided by 2 NW [mm / s] to obtain the time τn [s] from the origin to the nth intersection. XY in the figure is a tape coordinate system with the tape lower edge as a reference. Further, p-δt is the coordinate system of the trick play head locus, which is the horizontal axis-vertical axis in the diagram of the evaluation result.

<Data recording area and conversion of displacement> In the standard mode trick play, eight kinds of tape speeds are provided, and the SB of the burst center is equal to the number of intersections crossing the recording track for each tape speed. I need a number. Burst centers of different tape speeds may have very close SB numbers or overlap. Therefore, bursts used at each tape speed are allocated in a cycle of 48 tracks, and 112 SB of data is taken out between these 48 tracks. Therefore, the minimum required number of SBs that must be reproduced from one burst is the tape speed (number of intersections).
It varies from 8SB to 56SB. By standard,
In consideration of tape fluctuation and head touch, the recording area for trick play data is set to three times the required SB number. The product needs to manage tape fluctuations so that the head locus during trick play does not deviate from this data recording area.

Conversion of track displacement due to tape fluctuation will be described with reference to FIG. For tape pattern measurement, Rev
Since the linearity of the track recorded in the erse running state is measured, the widthwise displacement amount (δt) of the reverse head locus is an evaluation value of tape fluctuation. With the method other than the tape pattern measurement, when the recording track is displaced by δr in the width direction due to the tape fluctuation at the time of reverse, the areas A and B are A ′,
Move to B '. At this time, what is reproduced is not the theoretical area A but B'corresponding to B on the original recording track. Therefore, it seems that the reproduction area is displaced by Δt in the longitudinal direction on the head trajectory of Reverse. To be measured. On the other hand, when the reverse head locus is displaced by δt in the width direction, the reproduction area becomes B instead of A, so the displacement Δt of the reproduction area is
It can be converted to rse head locus displacement δt. An equation for converting Δt obtained from the data ID and the amount of time axis variation of the reproduction output into δt is given by the following equation using the intersection angle Φ [°] formed by the recording track and the head locus of trick play. δt = Δt ・ cosΦ ・ sinΦ (5)

<Evaluation by tape pattern measurement> As a method for evaluating tape fluctuation, tape pattern linearity measurement is the most general method. To detect the state of fluctuation,
The "drive characteristic evaluation device for recording tracks" for measuring the coordinates of the tracks in the longitudinal direction has been invented, which will be described with reference to FIG.

FIG. 5 shows the measurement result of the tape pattern recorded by forcibly sending a signal to the head while running the tape in the trick play state. As initially expected, the fluctuation in the center of the track was large, and the tape is thought to be in a state of string vibration.

<Evaluation Method Using Playback Data ID> Since the track number and SB number can be obtained from the playback data ID, the head locus position during trick play can be obtained by the track and SB numbers. The difference Δb [SB] between the theoretical burst center SB number b [SB] and the measured SB number is the amount of displacement in the longitudinal direction of the head locus in trick play. Since the unit of b and Δb is [SB], the head track length L [mm or μ for trick play is used.
m] must be used as the unit of length. The track longitudinal position p [mm] is obtained by the equation (4) by multiplying b [SB] by L / 356. Amount of displacement in the width direction (δt) [μm]
Is a displacement Δt in the longitudinal direction obtained by multiplying the difference Δb [SB] by L / 356, and thus the expression (5) is obtained by using the expression (3). p = b · L / 356 (6) δt = Δb · L / 356 · cosΦ · sinΦ (7) FIG. 6 shows evaluation results obtained from the trick play reproduction data ID. Similar to the measurement result with the tape pattern in FIG. 5, the fluctuation in the central portion is large.

<Evaluation Method by Measuring Time-Varying Fluctuation of Reproduction Output> Since the two methods explained in the background described above require a long time for measurement and data processing, the present invention was studied. . The abacus-shaped waveform is obtained as the reproduction output in the trick play. As a result of observing this well, it was found that it fluctuated in the time axis direction. When this fluctuating output waveform is stored in a digital oscilloscope, a band-shaped waveform having a fluctuation range as shown in FIG. 7 is obtained. Since the abacus-shaped apex is the burst center, if this is measured and the difference from the above theoretical value is obtained, the displacement amount in the head track width direction of the trick play can be calculated in the same manner as the evaluation by the ID of the reproduction data. it can. As described above, since the actual waveform has an ambiguous apex, it is the point of this measurement method to ensure the measurement accuracy by the following method.

<Explanation of the measuring method and measuring means A which are the main part of the present invention> As shown in FIG. 7, a horizontal line as a measurement reference is arbitrarily determined, and the drum FF rises (or falls) based on the time axis. Time τ1, τ2, τ3, τ4 [m
[s] is measured for each abacus bead.

<Explanation of the evaluation method and evaluation means B which are the main part of the present invention> As shown in FIG. 8, the average value τ of the four measured values is the burst center, and the difference δ1, τ3 and τ4 between τ1 and τ2.
The difference δ2 of each means the fluctuation range. Half of the average value δ of δ1 and δ2 is the one-sided fluctuation amount, and the maximum values τmax and τmin of the burst center are obtained by τ ± δ / 2. As shown in FIG. 8, these are the average values of τ1 and τ3 and τ2 and τ4.
Is the average value of.

The difference between τmax and τmin thus obtained and the burst center theoretical value τn is the time-axis fluctuation amount of the trick play output. Head trajectory longitudinal displacement Δt [μ
m] is a head speed of 2 NL [mm / s] based on the time axis fluctuation amount.
It is obtained by multiplying by However, τ ′ is τmin or τmax. Δt = 2 ・ N ・ L ・ (τ'-τn) (8)

Here, τn [s] is (2) as described above.
It is obtained by dividing the formula by 2NW. Furthermore, when re-converted in the width direction using the equation (3), the displacement amount δt that becomes the evaluation value
[Μm] is given by the following equation. However, when τ'is τmin, T
= Τ1 + τ3, and when τ'is τmax, T = τ2 + τ
Set to 4. δt = L ・ cosΦ ・ sinΦ × {N ・ T-n ・ ν ・ tanθ ・ tanθt / W ・ │tanθ-t anθt│} (9)

FIG. 9 shows the evaluation result obtained from the time axis fluctuation of the trick play reproduction output. Since the result was converted from the maximum value and the minimum value of the time axis fluctuation, it was represented by a line connecting the maximum value and the minimum value of the widthwise displacement. The above-mentioned three evaluation results were very well matched not only in the tendency of bending and the fluctuation range but also in the absolute value.

[0020]

As described above in detail, the present invention enables the tape running state during special reproduction to be evaluated easily and in a short time without measuring the linearity of the track pattern. Similarly, the running characteristics of the reference tape during special reproduction can be evaluated in a short time. Therefore, it is possible to reduce the process time and cost by applying it to the inspection process and adjustment process of the mass production line.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a conventional measurement state of a track pattern.

FIG. 2 is an explanatory diagram showing linearity of a conventional video track.

FIG. 3 is an explanatory diagram for calculating an intersection between a recording track and a reverse track.

FIG. 4 is an explanatory diagram showing a converted state of a recording track displacement.

FIG. 5 is an explanatory diagram showing evaluation results by tape pattern measurement.

FIG. 6 is an explanatory diagram showing an evaluation result based on a reproduction data ID.

FIG. 7 is an explanatory diagram showing an embodiment of a method and apparatus for evaluating running characteristics of a recording track according to the present invention.

FIG. 8 is an explanatory diagram showing a method of calculating the maximum value and the minimum value in the recording track running characteristic evaluation method and apparatus according to the present invention.

FIG. 9 is an explanatory diagram showing an evaluation result by measuring a time-axis fluctuation of output.

[Explanation of symbols]

W Effective data area (video width) SB sync block δt Head displacement in width direction θ Recording track angle τ1 to τ4 Time from rising (falling)

Claims (3)

(57) [Claims] 1. A by special reproduction I transected inclined tiger <br/> click recorded at normal speed on a recording medium, a tape running state at the time of special reproduction of the inclined tiger <br/> click In the method for evaluating the running characteristics of the recording track, the reproduction start position at which the special reproduction is performed, and the reproduction start position
A measurement step of measuring the time base fluctuation with the reproduction output of each generated track, and the maximum of the time base fluctuation measured by this measurement step.
An evaluation step of evaluating the recording track position with respect to the reproducing head based on the maximum value and the minimum value and evaluating the recording track traveling state during special reproduction. 2. By special playback I transected inclined tiger <br/> click recorded at normal speed on a recording medium, a tape running state at the time of special reproduction of the inclined tiger <br/> click In the device for evaluating the running characteristics of the recording track, the reproduction start position at which the special reproduction is performed, and the reproduction start position continuously.
Measuring means for measuring the time base fluctuation of the reproduced output of each track to be produced, the time measured by the measuring means
A running characteristic evaluation device for a recording track, comprising: an evaluation means for calculating the position of the recording track with respect to the reproducing head from the maximum value and the minimum value of the axis fluctuation and evaluating the running state of the recording track during special reproduction. 3. By linearity of the gradient tiger <br/> click recorded at the standard speed on the recording medium is special reproduction I traverse the inclined track <br/> click the reference tape is known A reference tape for evaluating the running state of the tape during the special reproduction of the inclined track
In the device for evaluating the running characteristics of the recording track, the reproduction start position at which the special reproduction is performed, and the reproduction start position continuously.
Measuring means for measuring the time base fluctuation with the reproduction output of each generated track, and the maximum value of the time base fluctuation measured by the measuring means.
And the minimum value, the position of the recording track with respect to the reproducing head is calculated, and an evaluation means for evaluating the running state of the reference tape during special reproduction is provided.